Etymology and definitions

The modern English word blue comes from the Middle English, bleu or blwe, which came from an Old French word bleu of Germanic origin (Frankish or possibly Old High Germanblao, "shining"). Bleu replaced Old English blaw. The root of these variations was the Proto-Germanic blæwaz, which was also the root of the Old Norse word bla and the modern Icelandicblár, and the Scandinavian word blå, but it can refer to other colours. A Scots and Scottish English word for "blue-grey" is blae, from the Middle English bla ("dark blue," from the Old Englishblæd). Ancient Greek lacked a word for colour blue and Homer called the colour of the sea "wine dark", except that the word kyanos (cyan) was used for dark blue enamel.

In the English language, blue may refer to the feeling of sadness. "He was feeling blue". This is because blue was related to rain, or storms, and in Greek mythology, the god Zeus would make rain when he was sad (crying), and a storm when he was angry. Kyanos was a name used in Ancient Greek to refer to dark blue tile (in English it means blue-green or cyan). The phrase "feeling blue" is linked also to a custom among many old deepwater sailing ships. If the ship lost the captain or any of the officers during its voyage, she would fly blue flags and have a blue band painted along her entire hull when returning to home port.

Many languages do not have separate terms for blue and or green, instead using a cover term for both (when the issue is discussed in linguistics, this cover term is sometimes called grue in English). Blue is commonly used on internet browsers to colour a link that has not been clicked; when a link has been clicked it changes yellow or orange or purple.

In science

Pigments

Traditionally, blue has been considered a primary colour in painting, with the secondary colour orange as its complement.

Scientific natural standards for blue

Emission spectrum of Cu2+

Electronic spectrum of aqua-ions Cu(H2O)52+

Animals

When an animal's coat is described as "blue", it usually refers to a shade of grey that takes on a bluish tint, a diluted variant of a pure black coat. This designation is used for a variety of animals, including dog coats, some rat coats, cat coats, some chicken breeds, and some horse coat colours.

Blue in human culture

English language

In the English language, blue often represents the human emotion of sadness, e.g. "He was feeling blue".

Music

The blues is a style of music originated by African Americans. Contrary to popular belief it is not called Blues because its lyrics are depressing but because its scale is inclusive of the "dark notes" or blue notes.

In 1999 Eiffel 65 released the song "Blue (Da Ba Dee)," a hugely popular Eurodance song which peaked at #2 on the Billboard Hot 100 in the United States, and reached #1 in 17 countries.

Mysticism

In the metaphysics of the "New Age Prophetess", Alice Bailey, in her system called the Seven Rays which classifies humans into seven different metaphysical psychological types, the "first ray" of "will-power" is represented by the color blue. People who have this metaphysical psychological type are said to be "on the Blue Ray".

Politics

Blue has been associated with a variety of political positions, often differentiated from communistred or anarchistblack. During the revolt in the Vendée against the French revolution, blues stood for the revolutionary forces, and white for the counter-revolutionaries. Later movements like the Breton blues used the colour to signify allegiance to the ideals of the revolution.

Religion

Blue in Hinduism: Many of the gods are depicted as having blue-coloured skin, particularly those associated with Vishnu, who is said to be the Preserver of the world and thus intimately connected to water. Krishna and Ram, Vishnu's avatars, are usually blue. Shiva, the Destroyer, is also depicted in light blue tones and is called neela kantha, or blue-throated, for having swallowed poison in an attempt to turn the tide of a battle between the gods and demons in the gods' favour.

Blue in Judaism: In the Torah, the Israelites were commanded to put fringes, tzitzit, on the corners of their garments, and to weave within these fringes a "twisted thread of blue (tekhelet)". In ancient days, this blue thread was made from a dye extracted from a Mediterranean snail called the hilazon. Maimonides claimed that this blue was the colour of "the clear noonday sky"; Rashi, the colour of the evening sky. According to several rabbinic sages, blue is the colour of God's Glory. Staring at this colour aids in mediation, bringing us a glimpse of the "pavement of sapphire, like the very sky for purity", which is a likeness of the Throne of God. (The Hebrew word for glory.) Many items in the Mishkan, the portable sanctuary in the wilderness, such as the menorah, many of the vessels, and the Ark of the Covenant, were covered with blue cloth when transported from place to place.

Symbolism

In Thailand, blue is associated with Friday on the Thai solar calendar. Anyone may wear blue on Fridays and anyone born on a Friday may adopt blue as their colour. The Thai language, however, is one that has had trouble distinguishing blue from green. The default word for Blue was recently สีน้ำเงิน literally, the colour of silver, a poetical reference to the silvery sheen of the deep blue sea. It now means Navy Blue, and the default word is now สีฟ้า literally, the colour of the sky.